Flow apparatus for the disruption of occlusions

ABSTRACT

The invention encompasses methods and apparatus for pumping fluid from one location to another through the repetitive expansion and collapse of bubbles generated as a result of the absorption of repetitive pulses of radiation in a fluid. This pumping phenomenon can be used to aid removal of a total or partial occlusion in a body passage by emulsifying the occlusion with acoustic shock and pressure waves or by causing mechanically disrupting the occlusive material.

[0001] This patent application is related to U.S. patent applicationSer. No. 08/955,858, entitled “PhotoAcoustic Removal of Occlusions FromBlood Vessels,” filed on Oct. 21, 1997, and to U.S. patent applicationSer. No. ______, entitled “Apparatus for Delivering Radiation Energy,”filed on Jul. 10, 1998, the entireties of both of which are hereinincorporated by reference.

BACKGROUND OF THE INVENTION

[0002] This invention relates generally to at least partial removal ofocclusive material from a body vessel with acoustic phenomena resultingfrom radiation energy pulses delivered through optical fiber media tothe vessel, and, more specifically, to methods and apparatus forgenerating flow within a body lumen to facilitate disruption ofocclusive material and recanalization of the occluded vessel. The term“clot” is used herein to refer to a thrombus, embolus or some othertotal or partial occlusion of a vessel. The term “emulsify” means tobreak apart or disrupt by photo-acoustic or mechanical or otherphenomena into particle(s) smaller than the original occlusive material.

[0003] Various embodiments for delivering radiation energy to bodylumens for ablative and photo-acoustic recanalization have beenpreviously disclosed. However, none of these embodiments are capable ofgenerating fluid flow within the vessel that can be used to improve thedegree of emulsification of an occlusion.

[0004] Therefore, it is an object of the present invention to providetechniques and apparatus that use pulsed radiation energy to generatefluid flow and/or to perform mechanical work within body lumens.

[0005] It is another object of the present invention to recanalize bodyvessels by disrupting total or partial occlusions using the disclosedflow techniques and apparatus.

[0006] It is a further object of the present invention to provideimproved techniques for removing obstructions from the human body,particularly clots from cerebral blood vessels, without causingcollateral damage to the vessel.

[0007] It is an object of the present invention to provide a method (andapparatus) for attracting rather than repelling occlusive material tothe photoacoustic source of disruption so as to potentially enhance theamount and/or degree of emulsification.

[0008] Some or all of these objects are achievable with the variousembodiments disclosed herein.

SUMMARY OF THE INVENTION

[0009] These and other objects are accomplished by the various aspectsof the present invention, wherein, briefly and generally, a devicehaving at least one inlet port, at least one outlet port (which may bedistal from or proximal to the external environment), and at least oneoptical fiber having a distal end positioned relative to the ports suchthat when pulsed radiation energy is delivered to a body vessel via theoptical fiber, fluid is caused to pass through the inlet port and totravel towards the outlet port, preferably past the optical fiber distalend. The repetitive formation and collapse of bubbles in the ambientfluid creates this flow phenomenon, which in turn results from therepetitive absorption of radiation pulses by the fluid. This flowphenomenon can be used to enhance the total or partial mechanicaldisruption or emulsification of occlusions with photoacoustic phenomena(all of which was previously described in the '858 application) bycausing ambient fluid and occlusive material to be drawn towards therecanalization apparatus. The invention can also result in localizedemulsification of occlusive material or partial or complete removal ofthat material from the body. The capability of radiation energy to causemechanical work to be performed is demonstrated by the presentinvention.

[0010] Multiple fibers can be arranged in such a manner that one or morefibers generate the pumping phenomenon and/or one or more fiberscontribute to the clot emulsification by generating the acousticphenomena described in the previous '858 application, and/or one or morefibers contribute to mechanical disruption of the clot as disclosedherein, for example.

[0011] The use of very small diameter optical fibers allows the desiredpumping to be achieved and acoustic waves to be generated with arelatively low amount of radiation pulse energy, thereby keeping theamount of heat input to the vessel at a low level. Proper thermalmanagement according to the present invention reduces the likelihood ofdamaging the walls of the blood vessel adjacent the occlusion, which isespecially important for the relatively thin walled vessels of the brainin which the present invention has application. Further, it is desirablethat radiation pulses not causing the desired fluid flow or not beingefficiently converted into the desired acoustic waves be terminated inorder to prevent inputting energy that heats the region without doinguseful work, as has been described in both previous applications.

[0012] Additional objects, features and advantages of the variousaspects of the present invention will be better understood from thefollowing description of its preferred embodiments, which descriptionshould be taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013]FIG. 1 is a longitudinal cross-section of a device fordemonstrating the capability of the invention to pump fluid.

[0014]FIG. 2 includes front and side partial cut-away views of anapparatus for circulating fluid through the distal end of a catheter.

[0015]FIG. 3 is a longitudinal cross-sectional view of the apparatusshown in FIG. 2.

[0016]FIG. 4 shows end and partial cut-away views of an apparatus forpumping fluid having multiple corresponding side slots and opticalfibers.

[0017]FIG. 5 shows the devices of FIGS. 2 and 7 disrupting an occlusionblocking a blood vessel, in cross-sectional view.

[0018]FIGS. 6A and 6B show simplified cross-sectional depictions ofother embodiments for circulating fluid through a catheter tip.

[0019]FIG. 7 consists of cross-sectional views of an apparatus forcirculating fluid through a catheter tip having a bundle of opticalfibers.

[0020]FIG. 8 depicts a cross-section of a variable tip catheter forregulating the amount of emulsification of an occlusion, shown incross-section.

[0021]FIG. 9 depicts a cross-section of an embodiment for circulatingfluid past a bundle of optical fibers.

[0022]FIGS. 10, 11A and 11B are simplified cross-sectional drawings ofmultiple-stage pumps used to pump fluid from one location to another.

[0023]FIGS. 12A and 12B depict simplified embodiments having multiplefibers for performing the pumping and chewing functions of the presentinvention.

[0024]FIG. 13 discloses a partial cut-away of a multiple fiberarrangement with a spring having a variable coil separation forming thedistal portion of the catheter.

[0025]FIGS. 14A and 14B illustrate side-views of devices that createsufficient jetting/pumping force to pull the fiber along the lumen of avessel.

[0026]FIG. 15A depicts a typical construction, in longitudinalcross-section, for a delivery catheter within the scope of the presentinvention. FIG. 15B shows an end-view of a flush fiber arrangement of anembodiment of the invention previously disclosed in the '858application. FIG. 15C depicts an end-view of a distal fiber arrangementof the present invention. FIGS. 15D and 15E detail in longitudinal andradial cross-sections the distal portion of a catheter having a fiberarrangement similar to that shown in FIGS. 12A and 13 within the scopeof the present invention.

[0027]FIGS. 16A and 16B illustrate in longitudinal and radial crosssections another embodiment of the distal portion of a catheter having afiber arrangement similar to that shown in FIGS. 15D and 15E.

[0028]FIG. 17 depicts a side view and longitudinal and radial cross5sectional views of an embodiment that relies on mechanical action of thedistal portions of the catheter to disrupt an occlusion.

[0029]FIG. 18 is a simplified depiction of an embodiment that relies onthe pumping phenomenon of the present invention to activate apiston-like device that can attack occlusive material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The present invention may, in general, be applied to the removalof material forming a partial or total occlusion of any human vessel butis particularly directed to opening a blood vessel that is totally orsubstantially blocked to the flow of blood. The previously-incorporatedpatent applications contain adequate descriptions of these generalapplications of the present invention, as well as the associatedpreferred configurations and operating parameters of the associatedtechnology, including, for example, the methods and apparatus fordelivering radiation energy from the laser to the optical fibers. Thosedisclosures apply equally to the present invention. However, it shouldbe understood that the present invention is not limited solely toaddressing the removal of occlusions from blood vessels but may havemuch broader applications in which flow is required or desired to begenerated, as would be obvious to one of skill in the art upon readingthis disclosure.

[0031] The present invention encompasses devices, including catheters,having the ability to “chew” through an occlusion by generating flowthrough an active distal portion to help draw the occlusion towards theoptical fibers (and thus towards the source of the acoustic pressure andshock waves and other forces). These catheters promise to be able tocreate a hole in an occlusion relatively larger than the OD of thecatheter or device being used.

[0032] Illustrating the types of flow generated by the current inventionis the apparatus shown in FIG. 1 comprising an optical fiber positionedinside a capillary tube. Mounting a fiber inside a capillary and firingshort duration, low energy, high frequency pulses of absorbableradiation energy creates several useful phenomena. First, generating aseries of bubbles 320 inside the sheath portion 322 of the capillary 324through short-duration, high-frequency, low energy radiation pulsesdelivered via optical fiber 326 to a fluid medium 328 capable ofabsorbing said radiation results in a rather violent fluid jetting fromthe distal end of the capillary in the direction shown by arrows 330.This is believed to result from the expansion of the bubble out of thecapillary and into the surrounding media, forcing outwards the slug offluid that originally occupied the portion of the capillary between thefiber tip and the distal end.

[0033] Second, a rather vigorous pumping action was observed during thedelivery of pulses of radiation to the fluid, in which fluid shot out ofthe top of the capillary as indicated by arrows 332. It is believed thatthis pumping action resulted from the repetitive collapse of bubbles. Itis believed that bubble collapse created a zone of low-pressure insideand adjacent to the distal portion of the capillary, which in turncaused surrounding fluid from the vessel to rush back into the capillaryto fill the void left by the collapsing bubble. It would appear easierfor fluid in the vessel to fill the void rather than fluid alreadypresent between the capillary wall and the fiber, because the formerwould experience less resistance to flow. It is believed that this rapidfluid refilling of the void facilitated the observed flow out of theproximal end of capillary. Capillary action may also have played a rolein this first embodiment, although capillary action is not necessary togenerate fluid movement, as further explained below.

[0034] These pumping/sucking phenomena can be utilized in a variety ofapparatus within the scope of the present invention. One such apparatusis shown in FIG. 2. Outer sheath 334 surrounds one or more opticalfibers 338 (three are shown for illustration) asymmetrically arranged inthe sheath. The distal tips of the fibers 338 are positioned relative tosheath side slot 336 in such a way that fluid present in the vessel issucked through side slot 336 and forced out the distal end of the sheath340. The dimensions of the side slot relative to the fiber size andposition are important, since if the fibers are located incorrectly, thepumping/sucking phenomenon is not observed. Satisfactory results areachieved with 12 50/55/65-micron fibers aligned side-by-side, with theirdistal tips even and extending about ⅓ mm (A) into a ⅔ mm-deep slot(A+B), which was ⅓ mm (C) from the distal tip of the 3French catheter of0.022 inch inner diameter. The slot was horizontally-sized to match thewidth of the 12-fiber bundle.

[0035] More particularly, 25 ns pulses (separated by about 200microsecond delays) of 532 nm wavelength radiation (selected for itsabsorption characteristics in blood) at a frequency of about 1 to 10 kHz(with 5 kHz preferred) were introduced through each of the twelve fibersin bursts of 1-3 pulses per fiber with an energy/pulse of about 100 to300 microJ and an average power of about 300 milliW. A frequency-doubledNd:YAG laser was used to produce the desired wavelength light. Clotadjacent slot 336 was sucked into the catheter and emulsified via acombination of shock and acoustic waves and turbulence caused by theexpansion and collapse of bubbles in the fluid. The emulsified materialwas then directed out of distal tip 340 and back into the fluid. It isbelieved that the edge of slot 336 also contributed to theemulsification by tearing the clot as it entered the turbulent regionadjacent the optical fiber tips. This mechanical disruption by the edgealso resulted from the bubbles hammering the clot against the edgeduring emulsification. As with all embodiments of the invention,however, the laser parameters, such as for example the pulse duration(for example between 5 and 30 ns), the wavelength, and the pulse energy,may be varied while still producing the desired phenomena.

[0036] The sucking motion at slot 336 creates a small vortex whichcirculates the emulsified material exiting end 340 back towards slot 336as distance C approaches less than 0.25 mm. This vortex action appearsto help keep the clot in contact with the slot once the clot is firstsucked in, and thus aids further emulsification.

[0037]FIG. 3 is a sectional view of a side-sucking apparatus similar tothat shown in FIG. 2. Distal tip 339 containing slot 336 is shownattached to outer catheter wall 334, typically with glue such ascyanoacrylate. The distal end of optional inner lumen walls 354 canterminate evenly with the tip of optical fiber(s) 338, which makespolishing of the fiber and catheter tips during catheter constructioneasier. As shown in FIG. 3, the volume of the outlet port 340 can bedecreased to form annular space 356 by inserting mandrel 350 throughinner lumen 352 formed by inner lumen walls 354. Decreasing this volumeincreases the velocity with which the emulsified clot is expelled fromthe outlet port 340. Typical materials of construction for the distaltip 339 include HDPE, LDPE, PET, polyimide, or even a metal. Typicaldistal dimensions are those of a 3French catheter, althoughproportionately larger or smaller devices may be constructed dependingupon the size of the vessel to be accessed.

[0038] An example of a catheter that may be used to deliver theembodiment shown in FIG. 3 as well as other embodiments of the inventionto the occlusion site is shown in FIG. 15A. The delivery catheter maycomprise two concentric tubes. The outer and inner tubes may comprisemultiple sections of decreasing flexibility. As an illustration, FIG.15A shows three outer sections and two inner, although othercombinations may be used. In a 150 cm catheter, for example, outersections 380, 382, and 384 may be anywhere from about 50-120 cm, about25-95 cm, and about 3-20 cm, respectively. Sections measuring 100 cm, 45cm, and 5 cm, for example, produce satisfactory results. A satisfactoryproximal outer section 380 comprises a composite of polyimide/spiralstainless steel tubing, with an inner diameter, for example, of 0.030 to0.040 inches, such as that made by Phelps-Dodge High-PerformanceConductor. Section 380 is glued with, for example, cyanoacrylate glue392, to mid outer section 382 comprising high-density polyethylene(HDPE). The HDPE facilitates joining the more rigid composite proximalouter sheath to the soft distal outer section 384, to which section 382is heat-fused. Section 384 comprises plasticized polyvinylchloride (PVC)of 60-65 shore A hardness. The inner tube comprises heat-sealed sections388 and 390 having lengths of anywhere from about 120-140 cm and about10-30 cm, respectively. Proximal inner section 388 has a materialselected to provide the desired rigidity and high burst pressure, suchas polypropylene tubing with flexual modulus (psi) of between about200,000 and about 250,000, with about 220,000 being typical. Distalinner section 390 may comprise a LD polyethylene/EVA blend. A 9% EVA/LDpolyethylene blend is satisfactory. To facilitate fluoroscopy, aradioopaque band marker 386, of gold or platinum, may be added to thedistal tip of the catheter. The marker band is glued to the distal outertubing, either outside of the distal outer portion or abutted againstthe distal edge to be flush with the outer wall. In general, the innertube materials are chosen for their burst properties, lubriciouscharacteristics and the outer for their rigidity or softness. Similarmaterials having similar relative flexibilities, softness, andlubricious properties may be substituted for those disclosed for theinner and outer tubes, as one of ordinary skill in the art wouldrecognize. Fibers 394 lie freely between the inner and outer concentrictubes, anchored in place only by the various glue points shown tofacilitate increased flexibility. A more rigid catheter may be achievedby injecting more glue at various points between the two tubes of theconstructed apparatus. One or more stainless steel or nitinol mandrel396 may also be inserted between the inner and outer tubes to createmore rigidity. The mandrel may be anchored in place by glue points 392and 398. A mandrel of 0.004 inches diameter may be used, although otherdiameters or a tapered mandrel would be acceptable, depending on thedesired degree of rigidity/flexibility of the construction.

[0039] A lubricious polymer coating, such as a hydrophilic coating orsilicone may be used to increase the ease of navigating the catheterthrough the guiding catheter and desired body lumens, and if introducedon the interior catheter walls, may enhance the trackability over anassociated guidewire.

[0040] In general, catheter construction is well-known to those of skillin the art and thus will not be described in great detail. In brief,after inserting the desired number of optical fibers and the innertubular member into the outer tubular member, the distal location ofeach fiber is adjusted so that the fiber distal ends occupy the desireddistal geometry. For example, the fibers can be sequentially arranged inthe same order as in the planar array of connector 310, so that theyoccupy the geometry shown in FIG. 15B (as an example of a configurationthat could be used for the embodiments disclosed in the previous '858patent application) or in FIG. 15C (that would correspond to theembodiment shown in FIGS. 2 and 3). To accomplish this, a light source,such as a marker laser, is used to identify which fiber distal endcorresponds to which fiber end positioned in the connector. As eachfiber is sequentially identified, its distal end is temporarily held inposition until all fibers have been identified and located. The fibersare then glued into position. Fibers can be held temporarily in positionby inserting each distal end into an alignment block having a series ofholes, each hole corresponding to a particular fiber. The block holdsthe fibers in position until they are glued.

[0041] Fluid such as biocompatible coolant (e.g., saline), radiographicagent or thrombolytic agent may be introduced through inner lumen 352during emulsification. Or, alternatively, fluid may be aspirated throughthe lumen to remove emulsified material from the body.

[0042]FIG. 4 depicts a catheter in which multiple fibers are mountedapproximately equidistant around the circumference of the catheter, eachfiber having its own inlet port in the side of the catheter tip. Whenthe fibers are fired individually with pulsed radiation, as describedherein, each fiber creates its own pumping action through itscorresponding side hole 358. As the position of the distal tip of anoptical fiber moves up its side hole towards the catheter's distal tip,the pumping phenomenon tends to change from sucking through the sidehole to blowing out of the side hole. When the tip of the catheter islocated in fluid adjacent the occlusion, such an arrangement of fiberscan cause the end of the catheter to gyrate around the clot, therebyincreasing the degree of emulsification of the clot relative to acatheter that remains relatively stationary. Gyration can be improved bydecreasing the number of fiber-and-slot combinations and increasing thenumber of consecutive pulses to each fiber, to permit the catheter tipto overcome inertia and to move through the fluid across the face of theclot. Gyration, however, is minimized if the catheter tip is locatedwithin an occlusion, due to high damping forces.

[0043]FIG. 5 shows how the device depicted in FIGS. 2 and 3 may be usedin a blood vessel 360 having a thrombus 362 and stenotic plaque 364. Forthe device shown in FIG. 2, the catheter can be punched through thethrombus while the optical fibers are dormant until the catheter reachesthe distal position shown. Pulsed radiation is then delivered down oneor more optical fibers 338, causing the thrombus to be sucked into slot336, emulsified, and then ejected 366 through the catheter distal tip.During the procedure, the catheter tip is slowly withdrawn throughthrombus 362, thereby revealing new thrombus to the catheter tip foremulsification. The speed of withdrawal is dependent upon the characterof the thrombus being emulsified and the geometry of the fibers andslot. The catheter should not be withdrawn so fast that the catheter'sability to chew through the thrombus is overwhelmed and the catheter tipbecomes clogged, thereby adversely affecting the degree ofemulsification. While FIG. 5 depicts thrusting the catheter tip of FIG.2 entirely through the thrombus before emulsification begins, it mayalso be used to emulsify thrombus by simply causing the catheter tip toapproach the proximal portion of the thrombus with the optical fibersalready firing into the ambient fluid so as to create the desiredacoustic phenomena and avoid direct ablation.

[0044] Another apparatus that exhibits the pumping/sucking phenomena isshown in FIG. 6A. Instead of a side-sucking apparatus, however, examplesof which are shown in FIGS. 2 and 3, FIG. 6A depicts an apparatus thatsucks through distal port 376 and discharges through rear ports 372.Optical fiber 368 is positioned within lumen 370 such that the distaltip of fiber 368 is located between distal opening 376 and rear openings372, and within sufficient distance of distal opening 376 such thatpulses of radiation delivered through optical fiber 368 cause fluidadjacent the distal port 376 to flow into the catheter and out of theexit ports 372.

[0045] The tapered portion of FIG. 6A has the advantages over a widerintake port, for example, up to about 400 microns and shown, forexample, in FIG. 7, of increasing the ultimate velocity of fluid-intakethrough the distal opening 376 and of minimizing the possibility ofpermitting clot to by-pass the emulsification zone at the optical fibertip(s). A typical necked portion of tubular member 370 can be formed,for example, by gently pulling heated PET tubing until it elongates andcreates a portion of narrower diameter, and then cutting the narrowerportion to form the distal opening 376. Distal openings of from about0.008 to 0.012 inches or larger can be made from 0.029 inch ID PETtubing. The necked portion typically extends over about 1 mm.

[0046]FIG. 6B depicts an alternative method of narrowing the distalinlet portion of a tubular member. Instead of necking the member, asimple doughnut-shaped object with desired inner diameter is glued tothe distal end of the member. Such object may be of any suitablematerial, such as polyimide or polyethylene tubing or some otherpolymeric material.

[0047] For front-sucking devices such as shown in FIGS. 6A and 6B, thepositioning of the distal tip of the optical fiber relative to thedistal opening become more sensitive as the distal opening diameterincreases. That is, the wider the opening, the smaller must be x. Atypical dimension between the fiber tip and the plane of the distal port376 (x) for a 0.008-inch wide distal port and a 50-micron diameteroptical fiber and the operating parameters disclosed herein, includingenergy per pulse of about 200 microJ, is between about 100 and 350microns. However, as the distal port diameter increases to about 0.015inches in diameter, the tolerance range decreases to between about 100to 150 microns, or 0.004 to 0.006 inches.

[0048] It is believed that this increase in positioning sensitivity forwider distal ports is related to the ability of a generated bubble tofill the space between the walls of the distal opening and thus togenerate the pumping force. That is, for the same operating conditionsand bubble volume, a bubble spanning the distal port would have asmaller depth (and thus a smaller range of x) for a largercross-sectional area tube than a bubble filling a smallercross-sectional area tube. Since the size of a bubble also depends uponthe amount of energy delivered to the absorbing fluid, however, thesensitivity in relative positioning between the fiber tip and the distalport can be decreased by increasing the energy per pulse, and thus thesize of the bubble generated per pulse.

[0049]FIG. 7 depicts another embodiment of the invention, in which abundle of multiple fibers 400 (with six optical fibers 402, for example,together with a central lumen for delivering fluid (for example,coolant) to, or aspirating fluid from, a blood vessel) is shownpositioned within an outer sheath 406 between the one or more side slots408 and the distal opening 410. If the fiber bundle 400 is positionedcentrally within sheath 406, as shown, it may be secured in place with aglue plug 412. When pulses of radiation are delivered through theoptical fibers in sequence to a fluid capable of absorbing theradiation, such that a series of transitory bubbles are first generatedand then collapse, flow is created from the distal opening 410 past thedistal end of the fiber bundle 400 and out of the oval side slots 408,as shown by the arrows in FIG. 7. Typical dimensions for thisconstruction include 5 mm for the portion of the catheter between thedistal opening 410 and the distal edge of the side slot 408; typicalside slots 408 can be between 5 mm and 10 mm; for a fiber bundle ofoutside diameter of between 0.01 and 0.02 inches, a catheter tipdiameter of about 1 mm (or 0.04 inches) was used. For the constructiondescribed herein to generate flow as described, the dimension labeled xbetween the distal tip and the tip of the optical fibers was betweenabout 0.004 and 0.006 inches. Typical materials of construction for thesheath are HDPE or PET or polyimide. As shown, sheath 406 optionally maycomprise part of catheter 401, which serves as the delivery vehicle forpositioning the apparatus adjacent an occlusion. However, catheter 401is not necessarily required, as long as some other sufficiently rigidand sufficiently flexible delivery means, such as the fiber bundle 400itself, is available.

[0050] A typical construction for the fiber bundle comprises a proximalportion having a spiral-wrap stainless steel coil sandwiched betweenpolyimide tubings, together with an outer layer of shrink-wrapped PET asdesired, and raid and distal portions having successively fewer layersof polyimide. The desired distal portion of acceptable outside diameterof between 0.01 and 0.02 inches (0.018 inch being preferred) comprisesoptical fibers positioned with cyanoacrylate glue between either twoconcentric polyimide tubes or one inner polyimide tube and an outerplatinum coil. Coolant or other fluid may be introduced through theinner polyimide tubing as desired or emulsified material can beaspirated.

[0051] The apparatus shown in FIGS. 6 and 7 may be used to emulsify anocclusion, by drawing the occlusion through the distal opening towardsthe optical fibers and emulsifying it in the manner described herein andas shown in FIG. 5. More specifically, the apparatus depicted in FIG. 7is shown in FIG. 5 attacking the proximal surface of occlusion 362.Emulsified clot 366 is shown ejected from side slots 408 after beingemulsified through a combination of shock wave and forces generated bythe expansion and collapse of transitory bubbles, all as described inthe earlier applications. Again, the user should take care not to pushthe apparatus of FIGS. 6 and 7 too quickly through the occlusion duringemulsification, so as to avoid overwhelming the apparatus.

[0052] The apparatus depicted in FIG. 8 addresses this potential issueby regulating the amount of clot being emulsified in the apparatus andthus helping to prevent the optical fibers from being overwhelmed andthe device from plugging. It comprises a variable size exit port(created by a loosely-coiled spring) that permits the apparatus eitherto suck or repel the clot surface. A stainless steel spring 420 is gluedto the distal end of the main catheter body 422. To the distal end ofspring 420 is glued a sheath 416 of polyimide or HDPE. Single opticalfiber 402 is positioned as shown such that the sheath 416 covers itstip. The tip of the optical fiber is positioned relative to the distalend of the sheath tip such that flow is generated through distal opening414 when radiation pulses are delivered through the optical fiber 402 tothe site of the occlusion. Lumen fluid and gelatinous clot are suckedthrough frontal inlet portion 414 of the distal catheter tip 416 towardthe optical fibers and emulsified as described herein, and then areejected through the open portion 418 of the spring 420. As the clot ispulled into the front portal 414, however, the clot presses against theouter surface of the distal sheath 416 of the apparatus, slightlycompressing the spring 420. The resiliency of the spring then biases thedistal sheath 414 away from the clot, thereby decreasing the amount ofclot being pulled into the device to be emulsified. As the device ismoved away from the clot, the suction caused by the absorption ofradiation energy into the lumen fluid again draws the clot towards thedevice and so continues the emulsification. In this manner, the user isaided in controlling the rate of emulsification through the apparatus'constant minor adjustments. Although only a single fiber is illustratedin FIG. 8, multiple fibers or a fiber bundle would also work for thisembodiment. Again, although this embodiment is shown mounted on acatheter 422, if no fluid needs to be delivered through a central lumento the activity site, as in most of these embodiments, then a catheteris not required to deliver the apparatus to the occlusion. Instead, anyappropriate, sufficiently-flexible means such as a simple wire, may beused to deliver the active portion of the apparatus to the occlusion. Atypical outer diameter of this apparatus would be between about 0.010and 0.020 inches, with a preferred outer diameter of about 0.018 inches.Portion 416 can be constructed out of any appropriate material such aspolyimide.

[0053] Spring 420 should have a spring constant k sufficient to preventthe fiber tip from directly contacting the clot as the clot gentlypresses against the outer surface of the distal sheath 416, so that adistance is ideally maintained between the tip of the fiber bundle 400and the outer edge of distal sheath. This distance may approximate0.004-0.006 inches for a 1-mm diameter sheath and optical fiber bundleof between 0.01 and 0.02 inches outside diameter. If the spring is soweak that the spring permits the optical fiber tips to travel beyond thespring/distal sheath arrangement, then this variable tip, spring-loadedapparatus can lose its advantage of controlling the rate ofemulsification and its ability to pump. A satisfactory spring for thispurpose may be made by winding about 140 kpsi Ultimate Tensile Strengthstainless steel or platinum wire of about 0.002 to 0.003 inches diameteraround a mandrel, and then stretching a section so that between about5-10 windings occupied about a 5 mm length. Obviously, other materialsand dimensions would produce other satisfactory springs to serve thepurposes described.

[0054] The apparatus shown in FIG. 9 can establish either forward orreverse flow depending on the position of the tip of the fiber opticbundle 400 relative to the distal opening 426. When the fiber opticbundle 400 is positioned within about 0.004 to 0.006 inches from thedistal opening 426 of the HDPE 1-mm diameter sheath 424, suction isdeveloped through opening 426 and fluid is expelled through rear opening428. Alternatively, if the distance between the distal tip of the fiberoptic apparatus is either increased or decreased outside of the 0.004 to0.006 inch range, the flow mechanism reverses, and the device developssuction through opening 428 and expels fluid through distal opening 426.The same would be true for differently sized devices, as long as thebubble size produced by the fiber/energy/operating conditionscombination were sufficiently large. Preferred constructions of cathetertips for preferred single-stage pumping/sucking/ emulsifying embodimentsof the present invention have been described. FIGS. 10, 11A and 11Bdepict multistage embodiments within the scope of the present invention.Multiple single stages 369 of the type depicted in FIG. 6 are connectedend-to-end to create a multiple-stage fluid pump of FIG. 11A. Fluidsucked through distal end 430 and into the first unit as a result ofradiation delivered to optical fiber 431 is then sucked from the firstunit through opening 432 and into the second unit by the action ofoptical fiber 433. Fluid in the second unit is then sucked throughopening 434 and into the third unit by the action of optical fiber 435,and so on. In this way, fluid passes from distal opening 430 down thelength of the multistage pump. FIG. 10 depicts each stage separated witha simple doughnut-shaped plate 442 rather than a nozzle 374. Firing ofthe various fibers should be controlled so that radiation is deliveredto each fiber tip only when the tip is immersed in fluid. This can beassured by priming the apparatus before use with fluid similar to thefluid in which the distal port is immersed, or firing the fibers onlywhen the fluid pumped from the vessel reaches each fiber. FIG. 11Adepicts the multistage pump with each stage having exit slots 446. FIG.11B is depicted with no exit slots. Instead, elements 444 are neckedportions of the outer tubing in which the fiber tips are positioned togenerate the sucking/pumping force. Such necked portions can be formedby heating and collapsing the polymeric tube 448 around a centralmandrel, and then, after cooling, removing the mandrel to leave the tubewith multiple collapsed portions. The fibers are then positioned andsecured inside each necked portion to form the multistage apparatus.

[0055] The apparatus of FIGS. 10 and 11A are depicted housed insideoptional tubular vessel 438 sealed on its distal end with imperviouswebbing 440. Tube 438 would contain any fluid pumped from the vessel inwhich the apparatus is positioned and prevents the pumped fluid,including any emulsified clot, from passing back into the vessel.Further, while each stage depicted has side slot in fluid communicationwith tube 438, such slots are not required.

[0056] Optionally, each stage could be separated by a valve—e.g., a leafvalve or a ball valve (not shown)—to prevent backflow from stage tostage or to direct or rectify fluid flow in a particular path. Suchvalves could also be used on the single stage versions, for example toseal off the exit port as the fiber was firing to ensure that fluid waspumped into the device only through the inlet port.

[0057] The pump head developed by a device such as that shown in FIG. 6Acan be determined by positioning that apparatus with its exit ports 372inside the tube-and-webbing arrangement shown in FIG. 11A. Fluid pumpedfrom a source will slowly fill the tube until the height of the fluidequals the pressure developed by the pumping mechanism. A single opticalfiber has generated heights of water equivalent to between 0.25 to 0.5psig. In addition, even for a nonoptimized set-up, pumping rates in theorder of about 0.2 cc/second were observed for an average power of about300 milliW.

[0058] Traditionally, pumping or suction of fluid within the body hasbeen achieved by having an external source of suction or pressuregenerate a corresponding negative or positive pressure inside the bodycavity. The fluid jetting/suction phenomenon of the present invention,however, illustrates how fluid can be pumped inside the body cavity (orin any other remote source of fluid) using radiation energy from aradiation source remote from the point of fluid flow. Pumping fluidusing the methods described is believed to result in relatively high,albeit fleeting, pumping pressures of perhaps several hundreds of psig.Such pressures were previously unattainable in the body without risk ofinjury.

[0059]FIGS. 12A and 12B show various fiber arrangements for minimizingthe ability of non-emulsified clot sucked into the apparatus through thedistal opening from escaping emulsification before being ejected throughthe side slots. Multiple fiber arrangements have the advantage ofpermitting the various functions of sucking and chewing/emulsifying tobe performed by different fibers. For example, in FIG. 12A, fiber 462,positioned relative to the distal opening 464 as described above forFIG. 6A, creates the pumping/sucking force drawing fluid and clottowards the distal opening 464. Fiber 460, positioned flush with, orslightly past distal opening 464, performs the function of emulsifyingthe clot but is incapable of contributing to the pumping phenomenonbecause of its location. This initial emulsification at the distalopening by fiber 460 helps to increase fluid flow through the opening,which in turn helps to cool the distal end of the apparatus. Of course,fiber 462 may also contribute to the actual emulsification in additionto creating the fluid flow, because of the accounting phenomenon beinggenerated by the repetitive pulses of radiation energy.

[0060] Fibers 466 perform further emulsification of clot particles asthey travel through the apparatus towards the side slots 468. However,if the fiber tips are longitudinally spaced too closely together, thenit may be possible that during the inactive period between pulses oftreatment laser radiation, clot particles that could benefit fromfurther emulsification might actually avoid further emulsificationbecause of the fluid velocity created by the apparatus' geometry andoperating conditions. Thus, fiber tips ideally are positionedlongitudinally relative to one another such that clot particles areincapable of bypassing all emulsification zones between consecutivepulses of radiation. For a construction of the type shown in FIGS. 6 and12 having a 0.012 inch diameter distal opening and a nominal 0.022 inchinner tube diameter and a typical energy level as described herein,fluid velocities in the order of 200 cm/sec have been observed. For aperiod between pulses of, for example, 200 microseconds, typical fibertip spacings are about 100-500 microns, depending on the duty cycle.That is, the longer between consecutive pulses, the farther apart thefiber distal tips need to be to minimize the chance of a particleavoiding all emulsification zones.

[0061]FIG. 13 discloses a variation of the embodiment shown in FIGS. 8and 12A. Spring 470, shown in partial cutaway to reveal the distalportion of the apparatus, is attached to the distal end of a suitablecatheter 472. The distal portion of spring 474 is tightly wound, andserves as a flexible tip to permit the device to navigate the tortuouspath of small diameter vessels in order to approach an occlusion. Theproximal portion of spring 476 has a larger coil separation than thedistal portion 474, and thus provides exit ports between adjacent coils,through which fluid and particles that are sucked in through distalopening 478 and emulsified can be ejected.

[0062] Fiber 480 is positioned inside the tightly-wound distal portion474 of the spring such that pulsed radiation delivered through fiber 480into the ambient fluid causes the fluid to be pumped through the distalopening 478 and out of the wider spring windings in spring portion 476.Fiber 482 is positioned substantially flush with the distal opening 478of the spring 470, and thus does not contribute to the pumping action.However, as fluid and occlusive material approach the device due to thesucking/pumping action caused by fiber 480, both fibers help to emulsifyportions of the occlusion. Furthermore, consistent with the discussionof FIGS. 12A and 12B, other longitudinally-offset fibers can bepositioned inside spring 470 to ensure complete emulsification. Thespring described in connection with FIG. 8 would also be satisfactoryhere. The desired coil separation could be achieved by inserting tworazor blades into the spring between coils a certain desired distanceapart, and stretching that portion of the spring until the desiredlinear coil density is reached.

[0063] Central lumen 484 is optional, and can be used to deliver fluidssuch as radiographic contrast agent or coolant to the site of theocclusion. Since all embodiments of the invention rely on the absorptionof select wavelength radiation energy into colored fluid such as blood,however, delivering fluid to the area of emulsification that alters thecolor of the vessel fluid through dilution or dissipation, may interferewith the absorption characteristics of the environment of the occlusion.Small delays in the emulsification process thus may be necessary topermit the area surrounding the environment to reperfuse with fluid,such as blood, that is capable of absorbing the wavelength light beingused, if fluid is introduced to the site of the occlusion through thecentral lumen. Alternatively, a tinted fluid compatible with the ambientconditions of the occlusion, may be introduced, so that absorption ofthe radiation energy will be minimally affected by the introduction ofother fluid.

[0064]FIGS. 14A and 14B disclose another embodiment of the invention. Asshown in FIG. 14A, cylindrical structure 486 is glued to the distal endof optical fiber 488. Examples of dimensions of tube 486 for a 50/55/65micron diameter optical fiber are about 2 mm in length and between about0.008 to 0.020 inches in diameter, with the distal optical fiber tipanchored within about 250 microns of the distal opening of cylinder 486.Delivering short duration, high frequency, low energy, pulsed radiation,as described herein, to fiber 488 causes fluid to be sucked throughdistal opening 490 and pumped out of proximal opening 492, creating aforce that tends to pull on fiber 488. The pumping or jetting action atthe distal end of fiber 480 causes the fiber to track upstream in ablood vessel, for example, as the fiber is paid out. Speeds estimated tobe about 10 cm/sec were observed using a single fiber. If the device isplaced downstream of an occlusion in a vessel, pulsed radiationdelivered to the fiber causes the device to approach the occlusion andcause emulsification as the clot passes within the emulsification zoneof the fiber.

[0065] A number of these devices can be bundled together, as shown forexample in FIG. 14B. When pulsed radiation is delivered to differentones of fibers 494, directional pull on the apparatus is produced as aresult of a non-central-axial force vector, created by thenon-centralized longitudinal thrust of the apparatus. The direction ofthe pull depends on the geometry of the fibers and which fiber is fired.This force vector can be controlled to influence how the apparatustracks across the face of an occlusion and causes emulsification ofdifferent areas of the occlusion.

[0066]FIGS. 15D and 15E are schematics of the distal end of the cathetershown in FIG. 15A (previously described) having a configuration with anactive tip portion similar to that shown in FIG. 12A, but having asingle “pumping” fiber 391 and three “chewing” fibers 394. Tube 389approximately 1 mm long and inner diameter of from about 0.014-0.018inches is glued between the distal inner walls 390 of inner diameter offrom about 0.020 to 0.029 inches. Tube 389 has a 0.35 to 0.5 mm-deepnotch 393 cut out of one side. The major distal portion of “pumping”fiber 391 is located between inner catheter wall 390 and outer catheterwall 384. The minor distal portion of fiber 391 passes between the jointof inner walls 387 and 390 and is secured to the outer surface of tube389 such that its distal tip is located about 0.25 mm from thedistalmost edge of tube 389, which is substantially coplanar with thedistalmost catheter plane 391 a. Tubular portion 387 (e.g., of lowdensity polyethylene) is glued on the distal ends of wall 390, so thatits distal edge is flush with the distal edge of tube 389. Marker band386 is added to facilitate visualization of the apparatus inside thebody during use. The overall distal diameter of the construction isabout 1 mm or 3French.

[0067] Side slot 397 is formed by skiving both the inner and outer wallsof the catheter, and serves to eject from the apparatus fluid andemulsified material pumped in through tube 389 as a result of the actionof fiber 391. The slot, typically of 3 to 10 mm long, may begin anywherefrom 1 to 10 mm from the distal tip of the catheter. As the distancebetween the distal tip of the catheter (and thus of the fiber 391) andthe slot increases, however, less pump head exists to eject pumped fluidand emulsified material. More than one slot may be used, as desired.Minimizing the spacing between fiber 391, tube 389 and tube 387 canimprove the pumping performance of fiber 391.

[0068] Fibers 394 can be positioned approximately flush with the distaltip of the catheter construction, and thus may not contribute to thepumping action. Instead of being secured with a glue plug as shown inFIG. 15A, however, fibers 394 are anchored to the side wall of eitherportion 387 or 390 using a small patch of glue 395. Thus, if fibers 394are positioned such that they both emulsify and create a sucking force,particulates sucked into the apparatus by fibers 394 can travel betweenthe inner and outer walls and ejected through side slot 397.Alternatively, the emulsified particulates might potentially be trappedbetween the walls and withdrawn from the patient after recanalization.

[0069] Although only one pumping fiber and three chewing fibers aredisclosed in this embodiment, other combinations of fibers are possible.Radiation pulses are distributed between the various fibers as desired.Two examples would be to evenly distribute groups of three pulses ofenergy with a 0.33 duty cycle between the four fibers, so that eachfiber receives 25% of the average energy delivered to the site of theocclusion. Alternatively, the average energy can be delivered evenlybetween the chewing and pumping fibers, so that each set of fibersreceives about 50% of the energy delivered. In the fiber arrangementdisclosed in FIGS. 15D and 15E, for example, a pulse train could bedelivered to the single pumping fiber after every delivery to one of thethree chewing fibers, so that for every pulse train received by aparticular chewing fiber, the pumping fiber would receive three.Distributing radiation pulses in this manner will help to increase thecontinuity of the pumping and emulsification actions, and will reduceperiods of inaction of the two. In addition, since the pumping fiberalone will tend to attract fluid/particles to the device, and thechewing fibers alone will tend to repel fluid/particles from the device,the pumping and chewing fibers can be controlled to address potentialclogging. In other words, if the device starts to become overwhelmedwith occlusive material, the pumping fiber could be turned off whileleaving the chewing fibers on, so that the material would be emulsifiedand/or repelled to clear the unit for further pumping/disruption.

[0070] Alternatively, the device could be used to probe the vessel forthe location of the clot with only the chewing fibers operating, andthen based on the duration information provided by the bubble feedbacksystem (bubble duration being less for clot than for blood), the pumpingfiber could be turned on once the device reached the vicinity of theclot. In other words, just as was described in the previous patentapplications that have been herein incorporated by reference, the pumperand/or the chewer fibers could be controlled using bubble feedbackinformation to avoid inefficiently introducing heat into the system.

[0071]FIGS. 16A and 16B depict an alternative construction to that shownin FIGS. 15D and 15E for a similar fiber arrangement. Nozzle 371 may bea solid piece of polyether block amide (such as PEBAX 7233, made byAtoChem)) with Shore D hardness of about 70, or some other similar,suitable polymeric material. Nozzle 371 is extruded as a tube with innerdiameter equal to the widest portion of the final nozzle construction,and with multiple lumens 369 created within the walls of the PEBAXconstruction. Because of this construction, the PEBAX cannot be toosoft, otherwise the lumens cannot hold their form and collapse. Theselumens ultimately will house optical fibers 391 and 394. The nozzle iscreated by gently heating the PEBAX material and collapsing it around amandrel with an outside diameter equal to the desired inner diameter ofthe distal portion of the nozzle. Typical dimensions of the nozzle tofit a 3French, 1-mm OD catheter are 0.022 inches proximal inner diameterto 0.018 inches distal inner diameter, about 2 mm in length, with a 1 mmlong necked portion. Nozzle 371 is secured to the inner wall of thecatheter with cyanoacrylate glue. “Pumper” fiber 391, present betweeninner and outer catheter walls as previously described, is positioned inone of the lumens 369 of nozzle 371 and terminates about 250 micronsfrom the distal plane of the apparatus such that it creates a pumpingmotion as described herein that results from pulsed radiation energy.The removed portion 375 of nozzle 371 permits the fiber tip 373 of“pumping” fiber 391 to extend slightly into the inlet port 379. Each of“chewing” fibers 394 is positioned in the pattern shown, for example,inside another lumen 369 in nozzle 371 flush with the distal plane ofthe apparatus. These fibers act to emulsify occlusive material beforesuch is drawn in through distal port 379 and ejected through side slot397.

[0072] Although side slot 297, as shown, consists of two skives, one ineach of the inner and outer wall of the catheter about 1 cm back fromthe apparatus' distal plane, the side slot may also comprise a series ofsmaller holes in either or both of the inner and outer walls. Replacinga skive in the inner wall, for example, with three smaller holesincreases the strength of the apparatus and may prevent collapse of thatportion of the device as it is pushed through a body lumen towards thesite of an occlusion. In addition, a fiber (not shown) can be positionedin the vicinity of the skives or smaller exit port holes, so thatacoustic phenomena generated by that fiber can help to force materialout of the exit port(s) and to prevent clogging in the exit port region.

[0073] An alternate set of “chewing” fibers is also shown in FIGS. 16Aand 16B. Fibers 377 could be used instead of, or in addition to, fibers394. Since fibers 377 have the last 1 mm or so of their distal tipsfree, they may have the advantage of fibers 394 of being able to betteremulsify occlusive material, since it is believed that free tipscontribute to better emulsification. Fibers 377 could be positioned byfeeding the fiber from in between the inner and outer catheter wallsinto a lumen 369 of nozzle 371, and then out of a slit in the outer wallof nozzle 371 (at which point it is glued) so that the distal fiber tipis approximately flush with the distal plane of the apparatus.

[0074] Marker band is shown in FIGS. 16A and 16B as mounted on thenozzle rather than on the outermost tubular material, another possiblelocation. The inner location as shown provides the advantage ofstreamlining the distal outer diameter of the apparatus.

[0075]FIG. 17 shows another embodiment of the present invention. Thisparticular embodiment further illustrates that the current invention canbe used to mechanically disrupt occlusive material wholly apart from anyemulsification action. Fiber 514 creates the pumping action throughdistal port 526. Instead of being flush with the distal catheter plane,as in previous embodiments, outer catheter wall 528 extends beyond innercatheter wall 524 by about 100 to 250 microns, for example, and issliced as shown to form flaps 518. Flaps 518 will be long enough so thatthe bubbles formed by the chewing fibers will be approximately centeredon the flaps, to generate sufficiently-levered force. For the dimensionsof the present example, flaps 518 might be 500 microns or more inlength, roughly centered on the distal tips of fibers 516, so that thedistal edge of a flap extends about 250 microns past distal plane 530,with one or two flaps per fiber for a 200-400 micron diameter cathetertip. When fibers 516 (nine shown for illustrative purposes) are fired inconjunction with the pumping action of fiber 514, flaps 518 vibrate.Holding this distal tip of the catheter gently against a mass ofocclusive material can cause the vibrating flaps slowly to abrade anddisrupt the surface of the occlusive material. The user should becareful not to overwhelm this capability by forcing the distal tip intothe occlusion, which causes damping and thus renders less effective thevibrating flaps. Typical materials of construction and dimensions forthis embodiment are as described herein.

[0076]FIG. 17 also illustrates an alternative method of mounting thepumping fiber 514. Tube 520, for example, may comprise polyimide tubingwith a nominal major length of about 1-mm, with portion 522 removedleaving a minor length of about 0.5-mm. Fiber 514 is glued to theoutside of tube 520 as shown so that the distal end extends about 250microns past the lowest point of tube 520, as shown. Tube 520 is gluedto the inside of the inner walls 524 of the distal tip of a catheter.Fibers 516 are secured between inner catheter wall 524 and outer wall528. Although fiber 514 is shown passing down the inner lumen of thecatheter shown in FIG. 17, fiber 514 can be positioned as shown in FIG.15D, such that only the minor distal portion is positioned in the innerlumen secured to tube 520, with the remaining portion of the fiber alsolocated between the catheter's inner and outer walls. This could beaccomplished, for example, by creating a small slit in the inner wall524 and passing the fiber from between the inner and outer catheterwalls through the slit and into the inner lumen where it could besecured to tube 520. If such a construction were used in the embodimentshown in FIGS. 15D and 15E, the distal tip of fiber 514 would still bepositioned about 250 microns from the distal plane of the catheter, forexample, such that delivery of short duration, high frequency, lowenergy pulses of radiation created the pumping phenomenon describedherein. In the embodiment shown in FIG. 17, the distal tip of fiber 514is positioned about 250 microns from the distal plane 530.

[0077]FIG. 18 depicts another embodiment within the scope of the presentinvention that relies on the pumping phenomenon created by therepetitive expansion and collapse of bubbles to activate a piston-likedevices for attacking and breaking-up occlusive material. Optical fiber500 is positioned relative to side hole 502 such that as short-duration,high frequency, low energy, pulsed radiation is delivered to the opticalfiber, ambient fluid is pumped through inlet port 502 and into internalsealed cavity 508. As hood 510 moves away from the fiber distal tiptowards the occlusion as a result of the fluid intake and the bubbleformation, port 502 seals. As hood 510 reaches its most remote position,port 506 opens to the vessel as a result of hole 504 aligning with port506. As the hood 510 tends to return to its original position to beginanother cycle, the extra fluid due to heat-induced expansion escapesthrough port 506 due to the compressive force caused by the elasticityof the hood. This return force can be aided by attaching a spring (notshown) to hood 510. Nubs 512 repetitively tear into the occlusion as thedevice pulsates.

[0078] In connection with the desire to avoid unnecessary heating at thedistal tip of the catheter, described briefly herein and in the patentapplications incorporated by reference, any of the preceding embodimentsmay include a thermocouple to monitor the temperature of the site of theocclusion during operation of the invention. Said thermocouple may, forexample, be positioned between the inner and outer catheter walls andflush with the distal tip or at another location between the inlet andoutlet ports, and could be used to trigger an audio or a visual alarm orto control the laser to avoid further heating of the operation site oncethe temperature of the distal tip exceeds, for example, 50 degreesCentigrade.

[0079] While the foregoing has described preferred illustrativeembodiments of the invention, other embodiments of the invention wouldbe obvious to one of ordinary skill in the art and are encompassed bythe following claims, which are of broader scope than the specificembodiments disclosed. Moreover, while the context in which the currentinvention has been explained concerns addressing a total or partialocclusion of a human vessel, the present invention, including itspumping/sucking aspects, would have application beyond the human body toany context in which it would be practical to move fluid from onelocation to another using radiation energy. Furthermore, while certainmaterials of construction have been identified herein, the inventionsare not particularly dependent upon the types of materials used.Finally, it may be possible to achieve some or all of the phenomenadescribed in the present disclosure by using forms of radiation otherthan pulsed radiation, such as continuous wave radiation. The disclosureof pulsed radiation herein should not be understood as limiting thescope of the present invention.

We claim:
 1. A method of pumping fluid, comprising: delivering radiationenergy to a point in a source of fluid; providing a flow channel;causing at least one transitory bubble to form in said fluid; andcausing a portion of said fluid in said lumen to move from around saidpoint via said flow channel to another location.
 2. The method of claim1, wherein said radiation energy comprises a plurality of pulses ofradiation energy.
 3. The method of claim 1, wherein said fluid ispresent in a body vessel.
 4. The method of claim 1, wherein said flowchannel comprises an inlet port proximal said point and an outlet port.5. The method of claim 4, wherein said fluid is moved through said inletport.
 6. The method of claim 1, wherein said transitory bubble forms asa result of said fluid directly absorbing said radiation energy.
 7. Themethod of claim 1, wherein said fluid is caused to move by the expansionand collapse of said at least one bubble.
 8. An apparatus for pumpingfluid in a body vessel, comprising: at least one optical fiber having adistal end, said fiber mounted in a flow channel having an inlet portand an outlet port, said inlet port located relative to said opticalfiber distal end such that radiation energy delivered to said fluid viasaid optical fiber causes a portion of said fluid to move through saidinlet.
 9. The apparatus of claim 8, wherein said radiation energycomprises a plurality of pulses of radiation energy.
 10. The apparatusof claim 9, wherein said fluid is caused to flow as a result of theexpansion and collapse of a plurality of bubbles formed by the fluidabsorbing said plurality of pulses of radiation energy.
 11. An apparatusfor disrupting occlusive material that at least partially blocks a bodyvessel to the flow of fluid, comprising: at least one optical fiberhaving a distal end positioned in said vessel in the vicinity of saidocclusive material; said fiber positioned in a sheath having an inletport and an outlet port, said distal end of said fiber positionedrelative to said inlet port such that introducing pulses of radiationenergy into said vessel via said fiber causes at least a portion of thevessel fluid or the occlusive material to enter the inlet port and atleast a portion of the occlusive material to be disrupted.
 12. Theapparatus of claim 11, wherein at least a first optical fiber generatesthe flow through the inlet port and at least a second optical fibercauses the portion of the occlusion to be emulsified.
 13. The apparatusof claim 11, wherein said first optical fiber is positioned moreradially-central in said sheath than said second optical fiber.
 14. Theapparatus of claim 11, wherein said a distal end of said second opticalfiber is positioned substantially flush with a distal opening of saidsheath.
 15. The apparatus of claim 11, wherein said sheath comprises aninner tubular portion, said first fiber mounted on said inner tubularportion such that said fluid tends to flow through the inlet port andthrough said inner tubular portion.
 16. A method for treating afluid-filled body vessel that is at least partially blocked by occlusivematerial, comprising: providing a flow channel having an inlet port andan outlet port, said inlet port positioned in the vicinity of saidocclusive material; delivering pulsed radiation energy to said vessel tocause a plurality of transitory bubbles to form in the vicinity of saidocclusive material; and causing at least a portion of said occlusivematerial to be disrupted.
 17. A catheter having a proximal end, a distalend, and an elongated member, said catheter further having at least twoopenings distal from said proximal end and in fluid communication withone another, the first of said openings for permitting fluid from avessel to enter said catheter and the second of said openings forpermitting said fluid to exit said catheter, said first opening in thevicinity of an optical fiber distal tip.